1. Field of the Invention
The present invention relates to electronic equipment for receiving external radio information for self-correction and other operations, and a reception control method of the electronic equipment. More specifically, the present invention relates to electronic equipment represented by a radio wave correction timepiece capable of receiving external time information and performing time correction, and further relates to a reception control method of the electronic equipment.
2. Description of the Related Art
Widely known electronic equipment capable of receiving external radio information to correct the operation and execute specific tasks typically includes a radio wave correction timepiece for receiving external time information to perform time correction.
Such a radio wave correction timepiece has a forced reception function for forcing the receiving of a standard wave for time correction in response to a user operating a winding crown or button. The radio wave correction timepiece typically also has an automatic reception function for performing an automatic time correction operation at a predetermined time for information reception. For example, the standard wave may be received at two o'clock in the morning every day.
Incidentally, the accuracy of a typical quartz timepieces in recent years is generally ±20 seconds or less in Loss/Gain Monthly-rate, and the accuracy of some highly accurate quartz timepieces is ±10 seconds or less in Loss/Gain Yearly-rate. Thus, little error occurs during the timepiece's daily operation, and time correction is often unnecessary, even when receiving the standard wave for time correction purposes.
As a result, automatic time correction is not necessary meaning that execution of the radio wave reception operation has been wasteful resulting in needless power consumption. In particular, it is to be noted that the information reception operation consumes the most power in timepieces, and it therefore shortens the service life of a battery, such as used in battery driven wristwatches.
In order to reduce wasteful power consumption, a technique is known in which the interval between information reception operations is changed according to time correction by radio wave reception at a certain time, such as described in Japanese Laid-open Patent Application Publication No. Hei7-159559.
Another problem associated with the use of radio wave reception for receiving a time correcting information is that if electromagnetic noise is generated by an external magnetic field or an internal generator, the generated noise affects external radio information, and in some cases, correct time information cannot be acquired. Further, when the timepiece attempts to receive externally transmitted radio information while, by chance, the user is within a building, a subway, an underground passage, or other enclosed area where it is very difficult to accurately receive radio transmissions, the user will not be able to receive the radio wave and correct time information will not be acquired. In the above Japanese Laid-open Patent Application Publication, there occur problems in that since time information cannot be acquired, the internal time cannot be corrected by time information in such cases, and correct time data is less easily output.
This problem occurs not only in the radio wave correction timepiece, but also various kinds of electronic equipment for controlling specific operations by using correct time information such as personal computers, electronic toys, and timers.
Additionally in the above mentioned Japanese Laid-open Patent Application Publication, the next information-reception period is determined by the correction quantity at a certain time point without taking into consideration any circumferential changes such as the characteristic, service environment, and/or secular changes of an electric circuit, and if the correction quantity in one radio wave reception is by chance very small, reception in each hour can be received after at most 24 hours. Thus, there is a possibility that the time setting of the equipment may deviate largely (Loss/Gain) before the next information-reception period. Therefore, there exists that problem that the correct time may not be displayed in the above mentioned Japanese Laid-open Patent Application Publication.
Also in this Japanese Laid-open Patent Application Publication, indication error is easily generated if the correction quantity is large, and this problem is dealt with only by shortening the reception interval of the radio wave. Thus, there is a problem that the number of radio wave receptions is not reduced on a whole as expected, and the reduction effect of power consumption is limited.